Crack detection in thick annular components using ultrasonic guided waves

This paper provides an overview of a study on circumferential guided waves in a thick annulus. Both steady state, time-harmonic waves and transient waves are considered. Several solution methods are reviewed and numerical solutions are presented for the propagation of ultrasonic circumferential waves in a thick, curved, two-dimensional annular waveguide. The modal content of the signal and the displacement profiles across the wall thickness are investigated. These studies provide valuable guidance in selecting optimal parameters for use in applications of the guided wave technique to the detection of cracks on the inner surface of annular components. Experimental results show that the technique can be used on parts with complex geometries (e.g. the pitch shaft of a helicopter) to detect cracks that would not be detectable by standard ultrasonic inspection.